She was arrested in August last year when it was alleged that Ian Brady, who along with Myra Hindley was jailed in 1966 after being found guilty of murdering five children, handed her a letter detailing where one of the children was buried.

The remains of Keith Bennett have never been discovered despite continued efforts by his now late mother Winnie Johnson.

John Dilworth, Head of the Crown Prosecution Service North West Complex Case Unit, said that the only offence that might have been committed by Ms Powell was preventing a lawful and decent burial, but that after careful consideration they have decided that she should not be charged.

Mr Dilworth added, "It cannot be established that she knew the contents of the letter referred to, that the letter in question existed or what information it might have contained.

The only evidence of the letter’s existence was in comments given by Ms Powell to an interviewer and she stated only that she believed_ it may_ contain information about Keith Bennett.

“Even if it could be proved that this letter existed, there is no evidence to suggest that Ms Powell ever knew the nature of its contents and there is insufficient evidence to prove that she genuinely believed it contained the information in question.

" As such, it could not be established in court that Ms Powell either prevented Keith Bennett’s burial or intended to do so."

Mr Dilworth said that they are aware that it is still a "very sensitive" matter for the relatives of Keith Bennett and that they have written to his brother to explain their decision.